Networks are complex, and their use is subject to a wide, inconsistent, and changing collection of technical requirements and options. For example, a given packet payload on a journey between two networked locations may be subject to multiple addressing formats, a plurality of transmission protocols, varied security options or requirements, intermittent hardware and software reliability, several particular priorities relative to other packets, and many different filtering rules.
The immense number of possible combinations of known and future networking technical options and requirements is overwhelming, even if one focuses only on features currently in use somewhere. Experienced network professionals sometimes indulge in guesswork and experimentation, because no one has yet fully mastered the enormous amount of information required to understand all networking requirements and options. At the same time, however, network professionals recognize that blindly trying different combinations will not consistently provide even a minimally functioning network architecture. And for practical purposes, simply trying different combinations of known features will almost never provide an efficient and reliable network architecture. In addition to the low probability of chancing upon a cost-effective and working combination of features, the efforts and expenses involved in setting up a network architecture are often substantial, so experimentation is severely hampered in practice.
Accordingly, effective network professionals use and depend on particular devices, systems, and processes which have been designed by experienced network innovators who have a proven track record of success.